The present invention relates to a display driver circuit, an electro-optical device, and a display drive method.
In electro-optical devices having a simple matrix liquid crystal panel, an improvement in response time and contrast is realized by using a multi-line selection (MLS) in which a plurality of scan electrodes are simultaneously selected. In the case of performing grayscale display by using MLS, frame rate control (hereinafter abbreviated as “FRC”), pulse width modulation (hereinafter abbreviated as “PWM”), or the like has been employed.
However, FRC has a problem in which flicker significantly occurs when the frame frequency is low. Therefore, the frame frequency must be increased when performing grayscale display by using FRC. In recent years, an increase in demand for video display using a liquid crystal panel makes it necessary to use liquid crystal materials having a high response time. Liquid crystal materials having a high response time are suitable for video display because the ON/OFF switching speed of the liquid crystal is increased. However, these materials tend to cause the switching of the liquid crystal to be more obvious. Therefore, the frame frequency must be further increased, whereby power consumption is increased.
On the contrary, PWM does not have problems relating to occurrence of flicker. However, PWM has problems relating to the influence of crosstalk. Specifically, in the case of driving a liquid crystal panel by using MLS, a root-mean-square value is applied to a liquid crystal layer. The voltage level of a scan electrode is changed when the voltage level of a signal electrode is changed. This decreases the root-mean-square value, whereby contrast deteriorates. The influence of crosstalk can be reduced by contriving a drive waveform of the voltage applied to the signal electrode. For example, the influence of crosstalk can be reduced without changing the root-mean-square value by shifting the drive waveform (to the right or the left) in each line or each frame. Moreover, the influence of crosstalk can be reduced by decreasing a change in voltage level of the scan electrode caused by a change in voltage level of the signal electrode by decreasing the number of change points of the drive waveform.